SEA SCORPION. 
183 
With age come distinct changes in the length of 
the head and of the jaws, which become larger, even 
in relative size; in the distance between the beginning 
of the first dorsal fin and that of the second, and in 
the distance between the former and the tip of the 
snout, both of which measurements also increase; in 
the distance between the ventral fins and the be- 
ginning of the anal fin and in that between the latter 
and the tip of the snout, which also increase; and 
lastly in the longitudinal diameter of the eye, which, 
on the other hand, diminishes with age according to 
the rule. In the length of the head scarcely any sexual 
difference can be detected; but in all the rest of these 
changes of growth the females take the higher place in 
the scale of development. The most constant external 
difference, between the sexes, the length of the ventral 
fins, naturally becomes more marked with age. It may 
be expressed, at least in specimens 150 mm. or more 
in length, as follows: in the males it is more, in the 
females less, than 18 % of the length of the body, or 
85 % of the distance between the beginning of the first 
dorsal fin and that of the second, or 33 % of the di- 
stance between the anal fin and the tip of the snout. 
Geographical separation, according to the above table, 
seems to be accompanied also by an increase in the 
length of the head in the specimens from Bohuslan and 
the Baltic, but shows its influence most clearly in the 
size of the eyes, the longitudinal diameter of which, in 
spite of the great changes due to age, is distinctly 
larger in specimens from more southern latitudes than 
in those from the Arctic regions. We must here add 
an observation made by Malmgren, given also by Day", 
that the Scandinavian specimens generally have a larger 
number of rays (usually 2 more) in the first dorsal fin 
than those which live further south. It has also been 
ascertained, says Lutken 6 , that the Arctic Sea Scorpion, 
as a rule, has 39 (in exceptional cases 36) vertebra.*, 
while the European variety has only 34 c or 36 'k In 
other fishes, of less variable form, these differences 
would certainly have been considered great enough to 
constitute specific characters — here we see them de- 
pendent on differences of age, sex or locality. Ac- 
cording to Day the species has “an evident tendency 
to degenerate the further it is from the Arctic region”, 
“ Fishes of Great Britain and Ireland , vol. I, p. 50. 
b Vid. Meddel. Naturli. For., Kbhvn 187G, p. 373. 
c Moreau, Poiss. Fr., Tome 2, p. 299. 
,l Malm, Gbgs, Boh. Fn., p. 389. 
e Pallas, ]. c. Mobius and Heincke state that it attains as 
but from a systematic point of view this “degeneracy” 
indicates a transition to the bubalis group. In the 
number of the vertebras Cottus scorpius occupies an 
intermediate position between Cottus quadricornis, which 
has 40, and Cottus bubalis , which has only 29 or 30. 
The variability of the Sea Scorpion thus suggests with- 
out ambiguity an explanation of the origin of its kind- 
red species. The course of development stops at dif- 
ferent stages, has its direction fixed by a sexual cha- 
racter, or bears the stamp of different external influ- 
ences due to different local circumstances. 
The usual size of the Sea Scorpion in Scandinavian 
waters is between 200 and 250 mm. In the Baltic and 
the Cattegat it seldom exceeds the latter measurement; 
but on the coast of Norway it grows somewhat larger, 
and in the Arctic regions it is said to attain a length 
of about 600 mnT. The length of the head (cf. the 
above table) is about 1 / 3 , its depth about V 5 , of the 
length of the body. The breadth of the head varies 
considerably, and depends on the greater or less ex- 
pansion of the gill-cover, which causes a great altera- 
tion in the appearance of the head. The gape is large, 
and the upper jaw somewhat projecting; it is moved 
chiefly by the help of the intermaxillary bones, which 
are rendered capable of some protrusion by their nasal 
process. They are covered by the labial skin, which 
is, as it were, rolled over them. Fine, cardiform teeth 
are closely set in the lower jaw, on the intermaxillary 
bones and on the head of the vomer, where they are 
arranged in a right angle pointing forwards. There 
are no teeth on the palatine bones or the tongue; but 
in the pharynx, above and below, we find two round 
patches, close to each other and covered with similar 
teeth. The upper pair of patches are larger, more per- 
fectly round and set almost in the same plane; the 
lower are smaller, flatter and set in different planes, 
together forming a right angle in an upward direction. 
Of the four branchial arches on each side the first three 
are completely free, the fourth generally united through- 
out its length to the back wall of the branchial cavity 
by a membrane behind it, which sometimes, however, 
leaves an opening free. The gill-rakers appear in the 
form of verrucose, spinous, bony protuberances; the 
branchial lam el lm are thin and low. The branchiostegal 
■reat a length as 1 metre. 
